Managing Symphylans with Rotation and Biopesticides

Commodities

• Agronomic: potatoes
• Vegetables: broccoli, greens (leafy)

Practices

• Crop Production: crop rotation
• Pest Management: biorational pesticides, botanical pesticides, economic threshold, integrated pest management, prevention, traps
• Production Systems: organic agriculture

Symphylans (Scutigerella immaculata Newport) are a persistent soil pest that affects many fresh vegetable and seed crops in Oregon’s Willamette Valley, resulting in poor stand establishment and economic damage. They are consistently identified as a major pest in the maritime Pacific Northwest, particularly in fields with fine-textured soils, high organic matter, and irrigation, which are common here. This project will demonstrate innovative monitoring and management strategies at OSU and on organic fresh vegetable and specialty seed farms. Our objectives are to: 1) Increase the adoption of symphylan monitoring; 2) Strengthen confidence in suppressive and tolerant crops; 3) Demonstrate judicious and effective use of biopesticides for symphylan management; and 4) Expand symphylan management knowledge among a broader audience.

We developed this project in close consultation with growers at a workshop in February 2024 and individual interviews. We will demonstrate symphylan bait sampling, the effectiveness of suppressive crops, and promising biopesticides identified in previous WSARE-funded projects and in Kaur’s ongoing research.

We propose a combination of OSU and on-farm demonstrations and field days that include interactive symphylan monitoring and management activities and peer-to-peer conversations around symphylan management. OSU demonstrations will include all components (monitoring, suppressive and tolerant crops, and biopesticides). Farmers will choose management methods based on monitoring results from their farm. This work will be shared more widely at an intensive symphylan management workshop and at grower conferences. Written information will also be distributed through newsletter articles and a new symphylan management Extension publication.

We will measure project outcomes with surveys at field days and workshops that evaluate knowledge gain and intention to adopt the research-based practices we promote. Collaborator interviews, notes from peer-to-peer conversations and the level of engagement with workshop and field day activities will provide qualitative evaluation information to complement survey results.

1. Increase adoption of symphylan monitoring. Bait sampling is effective but nuanced. When used correctly it can identify hot spots and guide management decisions. We will monitor an OSU demonstration site and collaborator’s fields for symphylans and associated predators and interpret results to guide crop rotations (e.g., susceptible, tolerant or suppressive crop) and biopesticide choices.
2. Strengthen confidence in the use of suppressive and tolerant crops. We will recommend areas to plant suppressive or tolerant crops based on monitoring results. Choices will vary between farms and may include potato cash crops, potatoes terminated early as a pest management cover crop, grass or cereal cover crops, or other suppressive plants identified in Kaur’s research. We will develop a list of suppressive and tolerant crops based on a review of scientific literature and the experiences of collaborators.
3. Demonstrate judicious and effective use of biopesticides for symphylan management. Drawing on Kaur’s ongoing insecticide efficacy trials, we will demonstrate promising biopesticides at OSU. We will present biopesticide options to collaborators monitor results on their farms. All our collaborators are certified organic or use organic methods, so this work will focus on NOP-compliant biopesticides. Some collaborators are reluctant to use any pesticides.
4. Increase symphylan management knowledge among a wider audience using the PAMS approach: Prevention, Avoidance, Monitoring, and Suppression (Coble 2003). We will host a wide range of events to share knowledge from this and related projects and publish at least one newsletter article and one peer-reviewed Extension publication.